Napa Valley AVA is an American Viticultural Area located in Napa County, California, United States. It is considered one of the world's premier wine regions, not just in terms of quality but in terms of high prices. Records of commercial wine production in the region date back to the nineteenth century, but premium wine production dates back only to the 1960s.

The combination of Mediterranean climate, geography and geology of the region are conducive to growing quality wine grapes. John Patchett established the Napa Valley's first commercial vineyard in 1858. In 1861 Charles Krug established another of Napa Valley's first commercial wineries in St. Helena. Viticulture in Napa suffered several setbacks in the late 19th and early 20th centuries, including an outbreak of the vine disease phylloxera, the institution of Prohibition, and the Great Depression. The wine industry in Napa Valley recovered, and helped by the results of the Paris Wine Tasting of 1976, came to be seen as capable of producing the best quality wine - equal to that of Old World wine regions. Napa Valley is now a major enotourism destination.

In 1976, the region got a boost from the Paris Wine Tasting of 1976, which featured a Napa Valley Chardonnay and Cabernet Sauvignon besting several famous French labels in a blind tasting format. The results of this tasting cemented the region's reputation as a producer of world class wines.

A modern outbreak of phylloxera was discovered in the valley in 1983 in a vineyard planted with AxR1 rootstock. Many growers seized upon this outbreak as an opportunity to switch to varieties that were better suited to the climate and soil. By the late 1990s nearly 75% of the affected vineyards had been replanted with phylloxera resistant rootstock. The growers in the region are currently channeling their energy to battle the Glassy-winged sharpshooter, a non-native pest that carries Pierce's disease.

Today Napa Valley features more than 450 wineries that grow grape varieties including Cabernet Sauvignon, Chardonnay, Pinot noir, Merlot, Zinfandel, among others. While winemakers may produce wines from specific AVAs within the valley, many wines are made as a blend from grapes grown on the valley floor and the surrounding hillsides.